Telephone repeater system



Aug. 10 192s. 1,595,159

0. B. JACOBS TELEPHONE REPEATER SYSTEM Filed August 25 1921 & Z4 2 2 4 2 INVENTOR Patented Au 10, 1926.

PATENT OFFICE.

oLrvEn. B. .rA'cons, or uonms PLAINS,- uEw JEBs Y, Assrenon To AMERICAN TELE- PHONE Ann TELEGRAPH conrm, A conronATIon or NEW YORK.

TELEPHONE nEPEA En sYsTEiu.

This invention relates to a repeater for telephone circuits, and one of its ob ects 1s to provide a new and improved repeater system adapted for operation between hnes 5 of different characteristic impedances. An-

other object of my invention is to provide a repeater with a single repeating element, or series of repeating elements, to operate between two lines, the necessary balancing being provided by suitable networks associated with the lines.

The invention will be better understood by reference to the following specificat on and the accompanying drawlng, in whlch Figure 1 is a diagram of a circult connection embodying my invention and F1gs. 2 and 3 are modifications thereof.

Referring to Fig. 1, the transmission l1nes 11 and 12, between which it is desired to repeat, may ;be any two lines having dlflerent characteristic impedances. These hues/are connected bymeans of the so-called 21 repeater circuit R, this repeater bein adapt- 1 ed for repeatin a message in two directions 25 with the use 0 one repeater element. For this connection, the we'll-lmown hybrid 0011, including. the windings 14, and 16, is used, the input terminals of the repeater element 17 being connected across the m dpoints of the windings 14 and 15 and the output of said element being connected across the winding 16, or vice versa. impulse coming from either direction w1ll be impressed on the input of the repeater element. The amplified output in the winding 16 will produce equal eflects in the wind ings 14 and 15 provided the lines 11 and 12 have the same impedance characteristics, and in view of the balanced condition of the windings, no effect will be producedby the winding 16 on the input of the-repeater element.

In case, however, the lines 11 and 12 are not similar, this balanced condition will not hold, and the repeater element or amplifier may'sing. In order to make it possible to connect two such different lines with a single repeater element, I connect across the line 11 impedance network 22, having thesame impedance characteristic Z as the line 12, ahd across the line 12 I connect an impedance 22 having the same characteristic Z, as the line 12. Under theseconditions the apparent impedance as seen from the repeater is exactly the same whether viewed in the direction of the line 11 or of the line 12, for in both cases there is seen the impedance resulting from two impedances, Z and Z connected in parallel.

In Fig. 2 I have shown amodification of the'above circuit. Here again the lines 11 and 12 of different impedance characteristics are connected by means of the repeater R, this latter being the same as that shown in more detail in Fig. 1. In this modification, the impedances are made to appear the same whether looking in the one direction or the other, by inserting a network in serles with the line on each side. On the one side, a network 24 having an impedance equal to that of the line 12 is inserted and on the other side a network 25 having an impedance equal to that of the line 11 is inserted. Under these conditions, the impedance, when viewed in either direction from the repeater, is equal to Z,|-Z,. Instead of connecting a single impedance Z on the one side, it is preferable to connect two impedances of /;Z,, in each line on the oneside, and similarly, to connect on the other side two impedances of the value ,z,, there being one of these in each conductor. This is for the purpose of maintaining better balance of the lines as a whole with respect to inductive disturbances other than those which may arise in the repeater element.

In Fig. 3 there is shown still a further modification of my invention, in which the impedances 21 and 22 are introduced into 99 thelines 1 1 and 12 inductively rather than conductively, use being made of the threecoil transformers 31and 32. This modification has the special advantage that telegraph or other low frequency signals can be passed-through the repeaters without encountering the impedance of the networks;

characteristic impedance, a two-way one-re peater circuitconnecting-said lines, and an auxiliary impedance associated with each line equal to the characteristic impedance of the other line.

2. In combination, two lines of different characteristic impedance, a two-way one-repeater circuit connecting said lines, and an auxiliary impedance connected with each 'line equal to the characteristic impedance of the other line.

3. In combination, two lines of different impedance characteristics, a two-way one-repeater circuit connecting said lines, an impedance network introduced in series relation in the first line and equal to the impedance of the second line and an impedance network introduced in series relation in the second line equal to the impedance of the first line.

4. In combination, two lines of diiferent impedance characteristics, a two-way one-repeater circuit connecting said lines, an impedance network inductively connected in series of the first line and an impedance network inductively connected in series in the second line.

5.-In combination, two lines of different impedance characterlstics, a two-way one-repeater circuit connecting said lines, an impedance network inductively connected in series in the first line and equal to the impedance of the second line, and an impedance network inductively connected in series in the second line andequal to the impedance of the first line.

6. In combination, two lines of difierent impedance characteristics, a two-way one-repeater circuit connecting said lines, a transformer having its primary connected in series relation in the first line and havin in its secondary circuit an impedance equaI to the impedance of the second line, and a transformer having its primary connected in series in the second line and having in its secondary circuit an impedance equal to that of the first line.

7. In combination, two lines of different characteristic impedance, a two-way one-repeater circuit connecting said lines, and two auxiliary impedances each in circuit with a respective line and each auxiliary impedance equal to the characteristic impedance of the other line whereby the impedance of each line and its associated im edance element is equalized to the impe ance of the other line andits associated impedance element.

In testimony whereof, I have si ed my August, 1921.

OLIVER B. JACOBS.

name to this specification this 2211 day of 

